Previously developed techniques for sutureless vascular anastomosis have required eversion of both the distal and proximal vessel. Since the human aorta, particularly when it is pathologically thickened, is not easily everted, a mechanical device has been developed for sutureless anastomosis of a vein segment to a non-everted aorta. This device was used in twenty dogs for chronic interposition of a reversed autologous vein segment between the aorta and the distal portion of the divided left subclavian artery.